As Hurricane Rita lashed the Florida Keys yesterday with strong winds and driving rain, inhabitants along the already-battered Gulf coast began to flee the storm.

Rita became a Category 1 hurricane yesterday morning with a top wind speed of 85mph, dumping up to 20cm (8in) of water on the low-lying Florida Keys island chain. Seawater splashed across US1, the road linking the islands, and wind hurled debris across roads, with forecasters warning of a two-metre (6ft) storm surge. To the south, Cuba evacuated 58,000 people from low-lying areas on its northern coast, including more than 6,000 in Havana.

Rita was thought likely to gain strength as it crossed the warm waters of the Gulf of Mexico. Forecasts predicted it could turn into another major hurricane that would most likely make landfall in Texas.

In Galveston, an island city off the coast of Texas wiped out by a hurricane 105 years ago with the loss of some 8,000 people, officials yesterday called for a voluntary evacuation. "Today is boarding up and decision day for Galvestonians," a city spokeswoman, Mary Jo Naschke, said.

Buses were laid on for people unable to leave on their own, taking them to shelters 100 miles north in Huntsville.

Residents in New Orleans also continued to eye the storm warily, after the city mayor, Ray Nagin, suspended his plan to start taking residents back to the city on Monday after warnings that Rita could follow Hurricane Katrina's course into the gulf and rupture the weakened levees.

Rick Perry, the Texas governor, yesterday recalled all emergency personnel helping with recovery from Katrina to prepare for Rita, including almost 1,200 Texas national guard members. "We're preparing for potential inland flooding and tornadoes by pre-positioning water rescue teams," a governor's office spokeswoman, Kathy Walt, said yesterday.

But authorities stressed that those fleeing the coastal area should bypass Houston after its mayor, Bill White, noted that it could lose power and was prone to flooding, and instead drive on to Dallas, San Antonio or Austin. Meanwhile, a Harris county judge, Robert Eckels, warned that the Houston Astrodome, which temporarily sheltered tens of thousands of Katrina refugees, could not be used in a storm because of its glass roof.

Katrina refugees still in shelters around Houston were to be flown to Arkansas, using private airlines, starting yesterday afternoon. Many evacuees have moved from shelters to private housing. "We could potentially be looking at taking an enormous amount of people from Houston," said Mike Huckabee, the Arkansas governor. "We're going to have to prepare in the event. It would tax us if we had to, but we would do it."

Arkansas already plays host to some 50,000 Katrina evacuees, most of them staying with friends and relatives.